400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-0790 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2007-01-4206 Fuel Economy Benefits of a High Torque Infinitely Variable Transmission for Commercial Vehicles David J Burtt Torotrak (Development) Ltd Commercial Vehicle Engineering Congress and Exhibition Rosemont, Illinois October 30-November 1, 2007 Downloaded from SAE International by University of British Columbia, Wednesday, August 01, 2018The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE's peer review process under th e supervision of the session organi zer. This process requires a minimum of three (3) reviews by industry experts. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-772-4028 Fax: 724-776-3036 For multiple print copies contact: SAE Customer Service Tel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-0790Email: [email protected] ISSN 0148-7191 Copyright © 2007 SAE International Positions and opinions advanced in this paper are those of the author(s ) and not necessarily those of SAE. The author is solely responsible for the content of th e paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publicat ion by SAE should send the manuscript or a 300 word abstract to Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by University of British Columbia, Wednesday, August 01, 2018Copyright © 2007 SAE International ABSTRACT Replacing a conventional automatic transmission with a high torque capacity, full-toroidal traction drive Infinitely Variable Transmission (IVT), delivers fuel economy benefits approaching those achieved by hybrid drivelines when a suitable balance be tween battery life and fuel economy is implemented, but with minimal additional on-cost, weight and complexity. These benefits are achieved by optimizing the engine operatin g conditions, eliminating the torque converter and removing torque interruptions during the gearshifts. Recent application of a non-op timal IVT to an Optare Solo bus (an 11,300kg European Midi-Bus) produced fuel savings of 19% over the standard Allison 5-speed automatic transmission. These measurements were independently performed by the internationally recognized Millbrook Proving Ground, UK. The precise control of the engine operating condition was demonstrated and this, in conjunction with the ability to decouple engine speed from wheel speed provides new opportunities to engine designers. This paper describes the operation of the IVT and the fuel economy benefits achieved in an Optare Solo European Midi-Bus application. Extending the IVT to satisfy larger commercial vehicles by creating a modular family of transmissions is discussed, together with the future hybridization potential of the IVT INTRODUCTION An Infinitely Variable Transmission (IVT) is able to decouple the engine speed from the vehicle wheel speed while accurately defining the load demand placed upon the engine. These features enable the engine to be controlled at its optimum operating condition to maximize fuel efficiency and minimize emissions. The single step of replacing a conventional Allison 5- speed automatic transmission in an Optare Solo 11,300kg European Midi-Bus with an un-optimized IVT produces a fuel saving of 19%, measured independently by the internationally recognized Millbrook Proving Ground, UK. Ful